Lactic acid bacteria (LAB) are intensively used in the dairy industry for making different animal milk fermented products such as cottage cheese. Cottage cheese accounts for approx. 700,000 tons of the world's 18.2 million tons consumed in 2008. In North America cottage cheese makes up approx. 12% of all cheese. Normally, cottage cheese cultures comprise homofermentative Lactococcus strains such as e.g. Lacotoccus lactis strains.
Relatively recently (within the last 3-5 years) Streptococcus thermophilus (ST) has been added to cottage cheese cultures. Addition of S. thermophilus may give a shorter fermentation time (e.g. shortened to around 4-5 hours). S. thermophilus strains are generally capable of expressing the enzyme urease (EC 3.5.1.5), which is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide (CO2) and ammonia (NH3). Milk comprises urea—accordingly, due to the production of the base NH3 by S. thermophilus there may be a temporary decrease in acidification speed during the fermentation of milk. In relation to this problem—NH3 induced temporary decrease in acidification speed—U.S. Pat. No. 6,962,721B1 (Texel, FR) describes that by using S. thermophilus that e.g. are not producing active urease enzyme (so-called “ur(−) strains”) one may get an improved acidification kinetic profile.
As technological background prior art that describes prior art known methods to make cottage cheese as such—may herein be mentioned U.S. Pat. No. 3,298,836 (published 1967); WO91/00690A1 and the article (“Gold Spot Dairy boost cottage cheese sales”, Dairy and Ice Cream Field, vol. 156, no. 6, 1973, pages 46-47).
U.S. Pat. No. 5,116,737 relates to bacteria that are producing active urease enzyme (may be termed “ur(+) strains”).